The present invention relates to the general field of rapid prototyping (RP) technology, and in particular, to stereolithography (SL) and fluid dispensing technologies, such as direct-write (DW) technologies.
RP technologies, also known as Solid Freeform Fabrication (SFF), layered manufacturing and other similar technologies enable the manufacture of complex three-dimensional (3D) parts. RP technologies, in particular, generally construct parts by building one layer at a time for use in, for example, the toy, automotive, aircraft and medical industries. Oftentimes prototypes made by RP technologies aid in research and development and provide a low cost alternative to traditional prototyping.
SL is one of the most widely used RP technologies known in the art. The resolution of SL machines and the ability of SL to manufacture highly complex 3D objects, make SL ideal for building both functional and non-functional prototypes. In particular, SL techniques provide economical, physical models of objects quickly prior to making more expensive finished parts. The models are readily customizable and design changes may be easily implemented.
SL generally involves a multi-stage process. For example, the first stage involves designing and inputting a precise mathematical and geometric description of the desired structure's shape into one of many computer-aided design (CAD) programs and saving the description in the standard transform language (STL) file format. In the second stage, the STL file is imported into SL machine-specific software (RP software). The RP software slices the design into layers and determines the placement of support structures to hold each cross-section in place while building the structure layer by layer. By computing build parameters, the RP software controls the part's fabrication. In the layer preparation stage, the build parameters for the desired part are translated into machine language. Finally, the machine language controls the SL machine to build a desired part and its support structures layer by layer. SL machines typically focus an ultraviolet (UV) laser onto a cross-section of a liquid photopolymer resin. The laser, in turn, selectively cures a resin to form a structure, layer by layer. Ultimately, the part is cleaned, the support structure is removed and the part is post-cured (typically exposed to UV) prior to completion.
SL technologies known in the art generally include, for example, a laser, a liquid level sensing system, laser beam optics and controllable scanning mirror system, a vertically movable platform, a resin retaining receptacle or vat and a recoating device. During the laser scanning phase, a series of optics and controllable scanning mirrors raster a UV laser beam to solidify a photopolymer resin. The subject 3D part is first attached to the platform by building a support structure with the platform in its topmost position. This step allows for misalignment between the platform and the surface of the liquid resin—once constructed, the base support structure is parallel with the surface of the liquid. When building the subject part simultaneously with its required support structure and after the laser beam completes a layer, the platform typically is vertically traversed downward a distance equal to the build layer thickness. After the platform is vertically traversed downward and prior to selectively curing the next layer, a recoating device is typically traversed horizontally across the part that deposits a uniform layer of liquid polymer across the part. The recoating device ensures that trapped spaces within the part are filled with liquid resin (which may be required for future build layers), and is used to maintain a constant build layer thickness. The process repeats as each layer is built. Complex-shaped parts are thus manufactured by repeating the layering process. Once complete, the part is typically raised out of the liquid polymer, the support structure is removed from the part and the part is cleaned and then post-cured. The operator may, however, need to sand, file or use some other finishing technique on the part in order to provide a specific surface finish to the structure, which may include painting, plating and/or coating the surface.
Although SL technologies for complex functional parts and prototypes have greatly improved in recent years, there is still a need to improve SL technologies for building functional electromechanical parts. There is a further need for achieving significant reductions in size, mass and manufacturing cycle times of low voltage electrical systems. Most RP systems allow building cycle sequences to be interrupted, thus opening the possibility of encapsulating electromechanical components within the model structure. For example, some have demonstrated the feasibility of encapsulating sensors and actuators in metal and polymer structures using Shape Deposition Manufacturing (SDM). Others have demonstrated systems for automatic dispensing of conductive, thermally curable media, such as DW inks, for maskless patterning of electronics. Limitations in speed and feature size, however, have prevented this technology's acceptance in the microelectronics industry. Recently, however, there have been several breakthroughs in DW ink dispensing for military applications which dispense advanced metallic inks through a hollow tip, precisely controlling the ink's flow and stopping points. Although there have been improvements in writing capabilities, many SL resins are incompatible, for example, with the high temperatures required to anneal, cure, dry and/or solidify DW inks. Thus, any attempts at integrating DW technologies with SL technologies have not been successful.
What is desired is a system and method for automated deposition of fluid media during SL on SL-created surfaces, automated curing of the media and continued building without the need to recalibrate or intermediately wash or cure. What is desired, therefore are improvements in part building technology and, in particular, improvements in the integration of curable media, such as DW inks, with SL technologies without contamination. Specifically, there is a need for low cost, efficient and easy-to-use SL processes that accommodate DW ink dispensing technology to fabricate, for example, complex 3D, multi-layered, high density, integrated and fully functional electromechanical systems. These electromechanical systems are more compact, less expensive and more reliable than their conventional predecessors. Additionally, by removing heavy cables, redundancy can easily be designed into a structure where previously it could not be, thus allowing significant size and weight savings for applications such as those in the aerospace and space industries. What is needed therefore is an integrated system capable of manufacturing fully functional electromechanical systems that are more compact, less expensive and more reliable than their conventional counter parts.
The present invention provides, for example, rapid development of circuitry to manufacture more compact components that provide advantages such as weight savings, self-assembly components, rapid manufacturing, and micro circuitry for aerospace, space, homeland security, national defense and a variety of other applications. The present invention also provides, for example, a system and method of integrating thermally curable media with SL without the need for intermediate washing, curing and/or drying. Thus, the present invention could easily be converted to make complex, 3D embedded circuitry, for example, without the addition of costly equipment.